Shane Flanagan and Trent Barrett have been stung with a combined $50,000 in fines from the NRL for comments made about referees following last weekend's finals losses.

Cronulla's Flanagan has been hit with a breach notice of $30,000 after he labelled the officiating as "disgraceful" in his team's elimination loss to North Queensland on Sunday.

Barrett's fine was $20,000 - more than the usual $10,000 - after he blamed officials for ending Manly's season in their loss to Penrith.

The fines come after NRL chief executive Todd Greenberg told the game to "grow up" in a line-in-the-sand speech against the two coaches - a view reiterated by head of football Brian Canavan.

"Our message is clear - no matter the significance of the match or the specific circumstances, coaches cannot cross the line," Canavan said.

"The integrity of our match officials and the game needs to be protected."

Manly have already confirmed they will weigh up whether to appeal the sanction, with both clubs having until next Tuesday to do so.

Barrett's fine comes after he invited referee's boss Tony Archer and the game's officials into his sheds to explain two controversial calls in his team's loss to Penrith.

The Manly coach was livid the bunker overruled an off-field call of try to deny Dylan Waler a crucial four-pointer for being offside, but didn't rule in his favour in Penrith centre Tyrone Peachey's effort to break a 10-10 deadlock late.

"We will be reviewing the basis upon which the NRL breach notice was issued and will be determining our position on the matter in the coming days," the club said in a statement.

Flanagan's larger fine comes after he also made remarks on the club's website, in an interview that was sent to members and also published online.

Flanagan produced a list of what he claimed to be at least 10 refereeing errors in the Sharks' extra-time loss to North Queensland, some of which have already been disproved.

Meanwhile the NRL insists Ashley Klein and Gavin Badger's non-selection for the two semi-finals this weekend is not a demotion as a result of Sunday's performance, but rather because there were two games, not four.